This invention relates to electrodynamic transducers. It is disclosed in the context of a moving coil loudspeaker, but is believed to have utility in other applications as well.
Various loudspeaker constructions are known. There are, for example, the constructions illustrated and described in U.S. Pat. Nos. 2,201,059; 2,295,483; 3,930,129; 4,146,756; 5,715,324; and, 5,729,616. This listing is not intended as a representation that a thorough search of the prior art has been conducted or that no more pertinent art than that listed above exists, and no such representation should be inferred.
An audio loudspeaker typically includes a magnet structure which provides a magnetic field across an air gap, a voice coil in the magnetic field in the air gap, and a diaphragm coupled to the voice coil to be reciprocated by the voice coil as audio frequency signal flows in the voice coil. Typically, the diaphragm is suspended around its outer perimeter from a supporting frame by a so-called surround, usually a half roll compliance which permits relatively free reciprocation of the diaphragm along the axis of the voice coil. Typically the diaphragm and the voice coil are also supported at the perimetrally inner boundary, or apex of the diaphragm, by a spider. The voice coil is mounted on a coil former which is attached to the apex of the diaphragm. The inner perimeter of the spider is attached at its inner perimeter to the joined coil former/apex, and at its outer perimeter to the frame or the magnet assembly, typically around the junction of the frame and magnet assembly.
The spider is typically constructed from phenolic resin-impregnated textile or the like. The impregnated textile is dried to remove the carrier from the phenolic resin and then hot pressed in a mold to set convolutions into the spider. These convolutions provide the necessary compliance to permit the same relatively free reciprocation of the apex along the axis of the voice coil. The convolutions typically are in the form of curved sections and generally straight sections. The curved sections may be arcs of a circle in cross section radially of the spider and loudspeaker, or segments of other curves. These will all be referred to herein as arcs. These arcs are typically uniform or, in some cases, uniformly decreasing or uniformly increasing, from adjacent the coil former to adjacent the frame and/or magnet assembly.
According to the invention, the arcs are neither uniform nor uniformly decreasing or increasing from adjacent the coil former to adjacent the frame/magnet assembly.
Illustratively, the arcs"" dimensions, for example, the lengths of circular arcs"" radii, are arranged somewhat randomly (quasi-randomly) from adjacent the coil former to adjacent the frame/magnet assembly.
Illustratively, the lengths of the arcs themselves are arranged quasi-randomly from adjacent the coil former to adjacent the frame/magnet assembly.
According to the invention, the lengths of the generally straight sections which, in many spider designs, connect adjacent arcs are neither uniform nor uniformly decreasing or increasing from adjacent the coil former to adjacent the frame/magnet assembly.
Illustratively, the lengths of the generally straight sections are arranged quasi-randomly from adjacent the coil former to adjacent the frame/magnet assembly.
According to the invention, an electrodynamic transducer includes a magnet assembly providing a magnetic field across an air gap, a voice coil, a coil former for supporting the voice coil in the air gap, and a diaphragm having an outer perimeter and an apex. The coil former is coupled to the apex so that current through the voice coil causing the voice coil to move in the air gap causes the diaphragm to move. A spider is coupled to the coil former to support the voice coil in the air gap. The spider has convolutions radially outward from the coil former. The convolutions include arcs and generally straight sections.
According to one aspect of the invention, the generally straight sections are of non-uniform length and of non-uniformly varying length with increasing distance from the coil former.
According to another aspect of the invention, the arcs have non-uniform and non-uniformly varying radii of curvature with increasing distance from the coil former.
Illustratively according to this aspect of the invention, the non-uniform radii of curvature are different radii of curvature.
According to another aspect of the invention, the arcs are of non-uniform length and of non-uniformly varying length with increasing distance from the coil former.
According to the invention, an electrodynamic transducer includes a frame, a magnet assembly providing a magnetic field across an air gap, a voice coil, a coil former for supporting the voice coil in the air gap, and a diaphragm having an outer perimeter and an apex. The coil former is coupled to the apex so that current through the voice coil causing the voice coil to move in the air gap causes the diaphragm to move. A surround is coupled to the outer perimeter and the frame to support the outer perimeter from the frame. The surround has convolutions radially outward from the outer perimeter. The convolutions include arcs and generally straight sections.
According to another aspect of the invention, the generally straight sections are of non-uniform length and of non-uniformly varying length with increasing distance from the outer perimeter.
According to another aspect of the invention, the arcs have non-uniform and non-uniformly varying radii of curvature with increasing distance from the coil former.
Illustratively according to this aspect of the invention, the non-uniform radii of curvature are quasi-random radii of curvature.
According to another aspect of the invention, the arcs are of non-uniform length and of non-uniformly varying length with increasing distance from the outer perimeter.